1. Field of the Invention
The invention pertains to the field of drain valves. More particularly, the invention pertains to valves and systems for draining gas-pressurized systems.
2. Description of Related Art
Many fire protection sprinkler systems are normally kept “dry”—that is, the pipes are not filled with water. This prevents problems with freezing pipes, drips, etc. The system is pressurized with a gas. Referring to FIG. 1, such systems comprise a source of pressurized gas (12) and water (11), connected to a controller (10). The sprinkler piping (13) is run around a facility to be protected, with a number of sprinkler heads (14) spaced along the piping (13). The controller (10) normally uses the pressurized gas (12) to pressurize the system piping (13). With the system pressurized with a dry gas, rather than water as in conventional wet systems, there is no problem with the pipes freezing and bursting in cold weather.
The sprinkler heads (14) are normally sealed, so that the pressure in the piping (13) is maintained. The heads (14) typically have a heat-operated closure of various kinds known to the art, so that in case of a fire the closure is opened and the sprinkler head is opened up to atmosphere. When this happens, the gas pressure in the piping drops as the sprinkler vents the piping to the atmosphere. Detecting this drop in pressure, the controller (10) connects the water source (11) to the piping (13), and the pipes quickly fill with water which flows out of the sprinkler heads (14) onto the fire. Usually the controller (10) will simultaneously trigger the facility's fire alarm system to call the fire department and alert the building's occupants.
The pressurized gas is most often simply compressed air, which naturally contains a quantity of moisture. As the air is compressed into the pipe, the moisture condenses out. Moisture also condenses on the pipe walls due to a reduction of temperature. Over time, a significant amount of condensate will tend to collect in the low spots in the system, which can have a deleterious effect on system operation, especially in cold weather where the condensate might freeze and make the system completely inoperative.
Accordingly, it is necessary for such systems to include some method of draining accumulated condensate.
A prior art fire protection drain system is sold as TYCO Model DD1, shown in U.S. Pat. No. 6,102,066, “Condensate drain for an automatic sprinkler system of the dry-pipe type” issued to Craig, et al. This assembly provides collection but not a fail-safe operation. If a power actuator is used, the actuators would have to be linked by a control system having a logic function whereby one valve cannot be opened when the other valve is open. The National Fire Protection Association, in NFPA 13 Section 5-14.2.5.2 and Section 5-14.2.5.3, define a construction that is essentially the Craig device. U.S. Pat. No. 3,329,215 “Dry Pipe Condensate Collector Containing Antifreeze” is an earlier manual two-valve system with a condensate chamber between two valves. There is nothing to prevent the two valves from opening simultaneously.
Craig and NFPA use two valves that are interconnected by a length of pipe that could serve as a collection chamber. As presently defined, these two valves may be opened simultaneously, which would allow gas pressure to flow from the pressurized system out the drain.
This problem is addressed in U.S. Pat. No. 6,443,173, “Automatic drain for a fire protection sprinkler system”, issued to Thompson in 2002. This is basically the NFPA or Willaig system, using motor-controlled valves under electronic control so that the two valves are opened sequentially and not together.
A floating ball valve establishes the position of the ball, and the ability to seal, by virtue of the geometry of the mating seats. A plug valve uses a tapered plug that is closely machined to match the taper in the body. The plug is then seated by forcing the plug into contact with the body.
Plug valves are known to the prior art which have one port, in the “plug”, that served both as the inlet and outlet. The interior of the “plug” served as the collection chamber. For examples of this type of valve, see U.S. Pat. No. 4,135,542 “Drain Device for Compressed Air Lines”, U.S. Pat. No. 4,331,268 “Seal for compressed air line drain device” or U.S. Pat. No. 578,718 “Automatic measuring, registering, and recording faucet”.
U.S. Pat. No. 4,058,240 “Automatic drain for compressed air systems” and related U.S. Pat. Nos. 4,383,545 and 4,473,092 are examples of this type of valve, in which the ball containing the condensate chamber is continuously rotated to fill and dump condensate—this type of system would represent a continual drain on the system pressure, as well, since the valve would dump a constant volume with each rotation, whether or not there was sufficient condensate to fill the ball.
U.S. Pat. No. 1,972,034, “Automatic Drain Valve” shows a float-controlled valve. When condensate or leakage fills a chamber, the float opens the valve to drain the chamber. Presumably, the pressure drop when the valve is opened would trigger the system, if this type of valve were used on a dry-type automatic sprinkler system.
U.S. Pat. No. 2,812,860, “Condensate Drain” uses a ball valve with a “T” shaped passage to connect a filter chamber and air reservoir to an air pressure tank. The filter chamber is continuously drained through a filter, which in the present application would appear to the system as a pressure leak which might trigger the sprinkler system.
U.S. Pat. No. 3,684,241, “Ball Valve” shows grooves in the ball of a ball valve but does not address the present invention's function of collection and never having a partially opened inlet port connected to a partially opened outlet port.
U.S. Pat. No. 5,285,809 “Drain Discharge Device” has two inlets and one outlet. The inlets connect to effluent discharging devices that discharge to a drain.
U.S. Pat. No. 5,445,187 “Condensate Traps” and U.S. Pat. No. 5,687,755 “Equipment Comprising a Condensate Trap” define valves which redirect flow. They do not provide for a means of collecting and storing the condensate. The valve has three functional positions. It connects the inlet directly to the outlet. It blocks the inlet. It directs the inlet to a steam trap device and then redirects the flow out of that device to the discharge port. It does not specify that the inlet port is always isolated from the outlet port. In fact, in two positions, the two ports are directly connected or connected by the steam trap.
“L” port and “T” port patterns are known porting patterns for ball valves. For example, the following ball valves are currently available:    Zipson model 501 R. In this valve, the ports will be cross-connected when the ball is in a partially closed position. This valve can trip the system if used in a pressurized system as in the invention.    Georg Fisher model P3376E. In this valve, there is a cross connection between the ports between 0 and 80 degrees. Flow is going from B→A and from B→C meaning it can also go from A→C. Flow A→C defines a failed valve and a tripped system.    Plast-O-Matic 3-way—This valve has the same design characteristics that wouldn't let it work in our application.